Bump Steering

[Stewart]

Does anybody know where I can get a rose joint kit for sierra steering rods

[Bob Tucker]

I doubt you will find a kit.

I assume you want to replace the tie rod end?

Rally design sell a big range, it will be a case of buy the parts you need

for your own kit.

http://www.rallydesign.co.uk/index.php?cPath=1113

CBS do them too....

http://www.carbuildersolutions.com/uk/filterSearch?q=rod+end&adv=true&adv=false&cid=0&isc=true&isc=false&mid=0&pf=&pt=&sid=true&sid=false#/pageSize=8&viewMode=grid&orderBy=0

 

Your heading says bump steer....is that your problem?

If so fitting rod ends is unlikely to solve it.

More info pls...

Edited September 21, 2016 by Bob Tucker

[Stewart]

I was told this morning by a racecar mechanic that because my lower suspension arm and my steering arm were not parallel this could cause bump steer and rose joints were the way to adjust them.

[Bob Tucker]

He is right....in a perfect world, parallel is best, but are you actually getting bumpsteer?

On a racecar setup rose joints may be a way to adjust it, but its more difficult

on a road car using production parts.

Steering & suspension set up is all about optimising many variables,

and for a road car accepting some compromises.

The most common way for our kitcars is to raise or lower the rack location.

Sorry but I dont know the Zero, so cant offer any concrete advice.

[Longboarder]

I suspect I know what your race mechanic was thinking. He would be thinking of shimming the rose joint up or down whilst testing for bump-steer. The cause is the steering rack is fitted to the chassis at the wrong height relative to the wishbone inner pivots. If you are experiencing bump steer from the front suspension then correction should firstly be to the fitted height of the steering rack, either higher or lower, whilst testing.

Removal/replacement of the outer end joint on the track-rod will change nothing except the toe and presuming you currently have the correct toe you would actually want that to stay the same.

Rose joints are not ideal on an all weather road car as they wear and shimming them up or down (having first reamed the taper in the steering arm out to parallel) seems to introduce a potentially weak point, especially if they need to be moved over an inch as they did on mine. See pic below. Can't really call them shims, they're towers. About 1.5" tall and further changes to the upper fitting to resecure the rack.

 

You can also get bump steer from the back end. Addressed by reducing negative camber and toe on the rear.

 

Nigel

[Guest mower man]

I shimmed the rack upwards around 2 mm on my car it did make a difference ! mick

[Guest 2b cruising]

If you go adjustable rose joint you will probably end up changing them for mot every year.

As our cars are among the heavier 7 style cars, rose joints are a little weak to suit the purpose.

Mick has used the best action to rectify the problem.

[Guest lotusPaul]

Just getting the steering arms and wish bones level is not all it's about.

 

Not only do you need to do that you must get the pivot moment correct.

 

To do this draw an imaginary line through the innner top and lower in board mounts.where the steering arm disects the imaginary is where the joint should be. It will then allow the steering arm to move independantly off the wishbone but at same time remain in parallel.

Thus controlling bump start.

[Peter Bell]

The above is fine in a straight line, of course as soon as any steering input is added it all goes to pot.

[Bob Tucker]

Plus the ball joint in the steering rack should ideally be directly in line with the lower & upper

wishbone pivots....

& the list goes on.....

Just get back to enjoying it as you were before....

the Zero is one of the best handling Hoods and can hold its own with many other 7 types

[Guest mower man]

If you want THE DEFINITIVE WORK on suspension beg borrow a copy of COMPETITION CAR SUSPENSION by ALLAN STANIFORTH it helped me and at least one more hoodie ,there is every thing you need and more mick

[Longboarder]

I missed that the car was a zero. The old robin hoods, stainless monocoques and 2b types usually need major suspension work as they were far from ideally designed. The zero is a different kettle of fish. Suspension was designed by Richard and compares well with the best sevens out there. I'm surprised you have bump steer problems. If you do then any changes you need to make will be in millimetres rather than centimetres and I would still advise starting on rack height after checking it is dead centre.(Track rod lengths exactly the same!) Also worth checking that the front suspension has been assembled exactly as designed.

 

Nigel

[Guest lotusPaul]

Bob.I think were saying the same thing. And Allans book is great. If you send me your email I'll photo the relevant pages.I can't post pics here.

[Bob Tucker]

Mick full marks for that book.

I have a number of suspension design & setup books that the library I worked for

decided to sell for 50p because they werent being lent out much....

Probably because I already had them at home.......

If you cant see it......you cant borrow it....LOL (Laugh Out Loud)

 

Seriously Stewrat,

I think you are looking for a solution to a problem you dont have......

[Bob Tucker]

The professional way to check is to remove the coilovers & move the wheels up & down.

 

The Hoodie way (my way) of checking bump steer,

is to park the car with the front wheels on a glossy page magazine (your choice)

Then bounce up & down hard on the suspension & carefully watch if the wheels

turn in (unlikley) or out (most likley) as the suspension goes up & down.

 

You should have seen what happened on my old sliding pillar setup.....truly terrifying.